Stabilized polymer compositions

ABSTRACT

Various polymers, such as polyacetal, polyolefine, polydiolefine, polyamide, polyurethane polyester, polyether, polyvinyl and polyhaloolefine are stabilized against heat, light and oxygen by adding thereto at least one pyrimidine base such as cytosine, cytidine and uracil.

United States Patent 1151 3,696,170 Ishida et al. 451 Oct, 3, 1972 1541STABILIZED POLYMER 3,277,045 10/1966 Bonvicinietal ..260/45.8COMPOSITIONS 3,281,392 10/1966 Oddo etal ..260/45.8 3,297,627 1/1967Hermann etal ..260/45.8 [72] Invent i g'gf fg' z fiz'g' I 3,313,7674/1967 Berardinelli etal......260/45.8 I g 3,394,102 7/1968 Wakasa m1...260/45.8 P 3,436,362 4/1969 Hayeretal. ..260/23.7 bmh 3,346,56110/1967 Boxer et al. ..260/211.5 TOkYMMfJaPa" 3,451,997 6/1969 Fujimoto..260/21 1.5 3,491,085 1/1970 Cook et a1. ..260/21 1.5 731 Asslgnee:Asahi Kasei Kogy Kabushiki 3,505,280 4/1970 Hermann et a1. ..260/45.8sha,0saka,Japan 3,516,985 6/1970 Walton etal. ..260/211.5 3,542,72911/1970 Murayama etal ..260/45.8 122 Flled: June 3, 1969 OTHERPUBUCATIONS [21] Appl 830114 Kokko et al., Journal of the AmericanChemical 1 I Society, Vol. 83, 1961, Pages 2909- 2,911, [30] ForeignApplication Priority Data QDIASCZ- June 4, [968 Japan ..43/37878 primaryExaWner Dona1d E. Czaja Assistant Examiner--R. A. .White U-S. F, L,Att0rney Burgess Dinklage & 260/857 D, 260/45.8 N, 260/45.9 P,

260/45.9 R, 260/45.95 57 ABSTRACT 51 Int. Cl. ..C08f 45/60, C08g 51/60[58] Field of Search ....260/45.8 N, 45.8 N0, 45.8 o, P E as Poll/metal260/251, 211.5, 857 F, 857 1., 857 D, 858 e 9 Pdyurethane F F polyether,polyvinyl and polyhaloolefine are stab1l1zed against heat, light andoxygen by adding thereto at [56] References cued least one pyrimidinebase such as cytosine, cytidine UNITED STATES PATENTS and uracil.

3,574,786 4/1971 lshida etal. ..260/857 14 Claims, N0 DrawingsSTABILIZED POLYMER COMPOSITIONS This invention relates to stabilizedpolymer compositions. More specifically. this invention relates tostabilized polymer composition which contains at least one pyrimidinebase. In general, organic polymers, when exposed to air and/orultraviolet ray, tend to be oxidized and thereby deteriorated ordegraderLOzone gas works to deteriorate most of polymers and heat alsois likely to catalyze the oxidative deterioration and decomposition ofthe polymers.

Especially, polymers such as polyacetal diolefinic synthetic rubbers,polyolefines, vinyl chloride polymer and copolymers, polyamides,polyurethanes and polyalkyleneoxides are susceptible to deterioration byheat and/or light. These polymers have usually been a made resistant tosuch deterioration or degradation by adding thereto a small amount ofvarious antioxidants and/or degradation inhibitors.

For this purpose, in general, phenol compounds and aromatic secondaryamino compounds have been used.

It is known that phenol compounds, when incorporated into polymermaterial, discolor polymer material. Further phenol compounds can noteffectively stabilize polyamides and polyurethanes. Especially,bisphenols themselves become discolored by the action of air and heat.

As for aromatic secondary amino compounds, they are widely used withnotable thermal stabilizing effect, but they also will causediscoloration of polymer materials when they are incorporated intopolymer materials.

in our pending US. Pat. Application, Ser. No. 803,504, filed on Feb. 27,1969, now US. Pat. No. 3 ,591 ,521 it is disclosed that S-aminouracil orS-aminostabilizes the organic materials against acidic degradationand/or ultraviolet ray degradation.

The present inventors have further made researches on more effectivestabilizers and found that cytosine, its derivatives, uracil and itsderivatives other than said S-aminouracil and S-aminocytosine inhibitdeterioration caused by heat, air and light. 5-amino uracil, 5-aminocytosin and their derivatives are good stabilizers for lowmolecular weight material, such as fats, gasoline, lard and vitamin buttheir stabilizing effects on high molecular material, namely polymermaterial, are not satisfactory. Especially the use of S-amino uracil,S-aminocytosine and their derivatives are not recommended on the polymermaterials which tend to be discolored by light.

Since in many cases polymer materials are commonly used in thecircumstances where they are exposed to light, especially U.V. ray, fora prolonged period, discoloration of them provides serious problems andshould be avoided as much as possible It has been proved that polymercomposition containing S-amino cytosine or their derivatives becomediscolored in some 50 hour exposure to U.V. ray, which is shown in oneof the examples of the present invention.

it is therefore an object of this invention to provide polymercompositions which are stable over a long period against light, heat,and/or oxygen.

Other and additional objects of this invention will become apparent froma consideration of this entire specification, including the claimsthereof.

In accordance with these objects, polymers are stabilized against suchdeterioration as caused by exposure to air, light and/or heat by addingthereto at least one pyrimidine base represented by a general formula OH)Njz N NH2 N NH? I I R and 0 I R respectively 0: 1 1 R2 12 in which, Ris a member selected from the group consisting of hydrogen atom,hydroxyl, amino and alkyl of one to 18 carbon atoms; R is a memberselected from the group consisting of hydrogen atom, alkyl of-one to 18carbon atoms and monosaccharide of five to six membered ring such asglucosyl, xylosyl and ribosyl and alkyl or acetyl-substitutedmonosaccharide of five to six membered ring; R is a member selected fromthe group consisting of hydrogen atom and alkyl of one to 18 carbonatoms; R, is a member selected from the group consisting of amino andhydroxyl: in case R is hydroxyl, R is a member selected from the groupconsisting of alkyl of one to 18 carbon atoms and monosaccharide of fiveto six membered ring such as glucosyl, xylosyl and ribosyl and alkyloracetylsubstituted monosaccharide of five to six carbon atoms, and R andR are as defined above.

The pyrimidine bases represented by the above formula are usually calledcytosine (4-amino-2(IH)- pyrimidone uracile(4-hydroxy-2-( lH)pyrimidone) and their derivatives.

The pyrimidine bases being non-toxic, the uses thereof are not limited.

Although, the pyrimidine bases can be synthesized, they may be easilyobtained by chemical decomposition of natural occurring nucleic acids.

The examples of pyrimidine bases of the present invention may include;Cytosine(4-amino-2-(ll-l )-pyrimidone), cytidine(lribosyl-2-keto-4-amino-pyrimidine), l-xylosyl-2-keto-4-amino-pyrimidine, l-glucosyl-2-keto-4-aminopyrimidine,l-(2,3,5-triacetyl ribosyl)-2-keto-4-aminopyrimidine,l-(2,3-isopropylidene ribosyl)-2-keto-4- amino-pyrimidine,l-ribosyl-2-keto-4-amino-5-methylpyrimidine, uridine(l-ribosyl-2-keto-44-hydroxylpyrimidine), thymidine(l-ribosyl-2-keto-4-hydroxyl-5- methyl-pyrimidine),l-glucosyl-2-keto-4-hydroxylpyrimidine,l-glucosyl-2-keto-4-hydroxyl-pyrimidine,l-glucosyl-2-keto-4-hydroxyl-5-methyl-pyrimidine.

As polymers, there may be mentioned polyolefins, polydiolefines,polyalkylene oxides, polyamide, polyurethanes, polyesters, polyethers,polythioethers, polyvinyl compounds, polyhaloolefines, polyacetals andtheir copolymers.

Especially, the pyrimidine bases of the present invention are effectiveto polyoxymethylene diacetate, polyoxymethylene diether, andcopolyoxymethylene having in its main chain and terminal positions otherunit such as oxyethylene, which are more easily discolored with lightthan other polymer material.

It is to be noted that, the polymer compositions containing pyrimidinebases of the present invention exhibit remarkable light resistance overa long period i.e., the appearance of the polymer compositions, does notchange even after 200 hour exposure to U.V. ray, while those containingconventional stabilizers such as amino uracil, S-amino cytosine andtheir derivatives become yellow in as early as 50 hours.

This light resistance of the polymer composition especially, over a longperiod being required to a greater extent, above stabilizing effectagainst light is highly estimated.

The pyrimidine bases themselves are stable to heat, lights, acidsalkalis, and can be employed in combination with other anti-oxidants,preservatives, plasticizers stabilizers, vulcanization-accelerators,fillers, antistatics, dyes, pigments and other common additives, in somecircumstances, exhibiting so called synergistic effects. The amount ofsaid additives may range from 0.001 to percent by weight based onpolymer material. Preferred combinations are those of (1) at least oneof pyrimidine bases of the present invention, (2) at least one of phenolcompounds and (3) at least one of nitrogen-containing compounds such aspolyamides, copolyamides, polyesteramides, dicarboxylic aciddihydrazide-urea-diamine-condensate and dicyandiamide, giving so calledsynergistic effect as embodied in examples.

Although a very small amount of the pyrimidine bases, even as low as0.001 percent by weight based on the polymer, can be effective, thepreferred amount of the pyrimidine bases ranges from 0.01 to 5 percentby weight based on the polymer. The upper limit of the amount set forthis determined by economic considerations and operational parameters, andis not an operative limitation.

Therefore, although the polymer can be effectively stabilized with 10percent or more by weight of the pyrimidine bases based on the polymer,the use of such a greater amount of them is usually not economicallyattractive.

The pyrimidine bases of the present invention may be incorporated intopolymers in any operable method and at any time in the course ofprocessing and preparation of the polymers, or it may be added to,applied to or dipped into the produced polymer.

The feature of the present invention can more fully be understood by thefollowing non-limiting illustrative examples.

In each example, is by weight based on the weight of polymer material,unless otherwise expressed.

EXAMPLES 1-16 (Stabilization of polyacetal) To 1 kg. of polyoxymethylenediacetate (abbreviated to POMD hereinafter) obtained by thepolymerization of formaldehyde and the subsequent acetylation withacetic anhydride and having intrinsic viscosity 2.00 as measured at 60C. in a mixture solution of equal amount of tetrachloroethane andp-chlorophenol, was added cytidine (cytosine riboside) or uridine(uracil riboside) at amount specified in Table 1 to prepare polymercompositions. The composition was throughly mixed and thethermostability and light-resistance of the composition were measured.Comparative test To 1 kg. of POMD as identified above, there was addedas a thermal stabilizer, at least one of copolyamides,polyaminotriazole, urea, diphenylamine, ureaadipic aciddihydrazide-hexamethylene diamine condensate and pyrimidine bases toprepare polymer composition. The composition was thoroughly mixed. Themeasurement of the thermal stability and light resistance by means ofFade-o-Meter was conducted. The results are shown in Table 1. In eachexample, 0.2 percent of 2,2-methylene-bis(4-methyl-6-tert-butylphenol)was contained in the composition.

TABLE 1 Amount 2 added R S(ml./ Val- (%)(I) (%)(2)g )(3) ll) Lightresistance Ex. Nos. Additives l Urea 2.0 discolored not changed 94.3very large 0.5 99.0 98 not changed slightly discolored not changed 85dark brown 82.0 very large 9 Copolyamide of hexamethylene adipamide,hexamethylene sebacamide and caprolactam and Diphenyl amine l0Polyaminotriazole prepared from sebacic acid hydrazide v and Diphenylamine 0.

ll Urea-adipic 1 acid dihydrazidehexamethylenediamine condensate andDiphenyl amine l2 Copolyamide of hexamethylene adipamide, hexamethylenesebacamide and caprolactam and Cytidine (cytosine riboside) l3Polyaminotriazole prepared from sebacic acid hydrazide and Cylidine(Cytosine riboside) l4 Urea-adipic acid dihydrazidehexamethylenediaminecondensate and 98.70 97 not changed 99.3 8 99 not changedCytidine (cytosine riboside) l Urea-adipic aciddihydrazide-hexamethylene diaminecondensate and Uridine (uracilriboside) 16 No additives very large slightly discolored Note: is byweight based on the weight of polyoxymethylene diacetate R (70) ispercentage of residue after heat-treating the polymer composition at220C. in the air for 60 minutes.

*8 (ml./g.) is amount of gas generated in terms of ml. per. gram of thepolymer composition after heat-treating the same at 220C. in ahypodermic syringe Z value ie i the w ed by of Hunter colorimeter, of a3 mm. thick plate injection-molded at 190C. of each composition.

""Light resistance was measured for the sample plate as formed above,,by means of Fade-O-meter. and was indicated by the appearance of theplate after 192 hours exposure to light.

"This condensate is disclosed in US. Patent Application Serial. No.785599, now Patent 3,574,786.

From the results shown in Table 1, it is evident that both cytidine anduridine can afford to POMD re markable resistance against heat andultraviolet ray, giving thermal stabilized and light-stabilizedpolyoxymethylene composition.

It is further noted that the use of polyamide or ureaadipic aciddihydrazide-hexamethylene diamine condensate in conjunction with thepyrimidine base of the present invention exhibited remarkablesynergistic effect on POMD.

EXAMPLE l7 (Stabilization of Polyacetal) A l l. three-necked flask wascharged with a mixture of 258 parts of tetradecanedioic aciddihydrazide, 116 parts of hexamethylene diamine and 50 parts of urea.The content was heated to melt at 200 C. giving colorless transparentliquid. Then the melt mixture was heated to react at 200 C for 300minutes in nitrogen stream, to gradually increase its viscosity, turningto ple plate. This reworking operation was repeated five times andneither discoloration nor degradation in pro perties was observed.Comparative test: The compara tive test was conducted in the same manneras in Example 17, except that the components of the sample mixture werealtered. A mixture of 1 kg. of POMD as hazy white in the latter halfperiod until at last viscous translucent liquid was obtained. Then theliquid was allowed to react for another 300 minutes under vacuum of lmml-lg to finish the reaction, yielding white mass of polymer in 250parts.

To 1 kg. of POMD having 1.70 intrinsic viscosity there were added 1.0percent of above-obtained product in powder from, 0.5 percent of4,4'-butylidene-bis( 3-methyl-6-tert-butyl l -formyloxy-benzene) theformula tert. Bu EH tert. Bu

H orroo a 7 -oon0 cm CH8 and 0.1 percent of cytidine.

The whole was completely kneaded and then formed at 190 C. byinjection-molding into 3 mm. thick sample plates.

A portion of thus obtained sample plate was then heated in the air for120 minutes at 222 C., resulting in a weight loss of 1.3 percent. Thewhiteness in terms of Z value was'99. Then in sample plate was crushedinto powder and injection-molded into an equivalent sam- 5(Stabilization of polyurethane) EXAMPLE l8 (Stabilization ofcopolyacetal) To 1 kg. of polyoxymethylene containing approximately 2.0percent by weight of oxyethylene unit, was added 5 percent of2,2'-methylene-bis(4-methyl-6-tertbutyl phenol). The whole mixture wasdivided into 4 equivalent portions, into each of which was incorporatedan additive as specified in Table 2 to prepare sample composition. Eachsample composition was throughly mixed and kneaded in a roll mill at 180C and then formed into a 0.5 mm. thick sample sheet by means of a hotpress. Each sample sheet was exposed to ultraviolet ray radiated fromFade-O-Meter and the yellowing of the sheet was observed as anindication of discoloration.

TABLE 2 Sample Additives Light-resistance K222 (a) 0.08% ofdicyandiamide yellow 0.03 (b) 0.03% of maleinamide and v 1 0.08% ofdicyandiamine yellow 0.02 (c) 0.05% of cytidine not changed 0.02 (d)0.05% of cytidine not changed 0.02

0.05% of dicyandiamide Light-resistance is indicated by appearance of asample sheet observed after 192 hour exposure to the light.

K222 is rate constant for thermal deterioration and is represented by aweight loss in terms of of a sample sheet measured after heat treatmentthereof at 222C for l min.

EXAMPLE 19 A three-necked l l. flask was charged with 100 g. ofhydroxyl-terminated low molecular weight glycol prepared by the reactionbetween polytetramethylene oxide diglycol having molecular weight ofapproximately 1,000 and 2,4-toluylenediisocyanate and 16.8 g ofmethylene-bis(4-phenyl isocyanate). The mixture was heated to reactat C.for 1 hour to give prepolymer, which was then dissolved in methylenechloride together with 13.9 g. of methylene bis(4-phen ylisocyanate). Tothe solution was added a smaller amount of ethylene diamine toprecipitate produced polyurethane.

Tensile strength of the sample sheet exposed to V. ray

Tensile strength of the sample sheet unexposed t U.V. ray

and the discoloration of the sample sheet were measured as indicationsof light resistance of the sample.

While a cut-off portion of the same sheet was maintained at 150 C in theair for 6 hours and the endurable stability defined by the formula;

Tensile strength of the sample heat-treated Tensile strength of theuntreated sample X 0 and the discoloration of the portion were measuredas indications of thermal stability of the sample.

The results are tabulated in Table 3.

TABLE 3 Light resistance Thermal stability Endurable Endurable stabilitdiscolorstability discolor- Sample Additives ation ation a No additivesbrown 67 yellow b Cytidine 87 not changed 92 not changed c Uridine 84slightly 90 scarcely discolored discolored d l,l,3-tris-(2- 58 yellow 80slightly (commethyl 4- yellow parative hydroxy-5-terttest) dibutylphenyl) butane (on sale) Note: Discoloration was observed in the samemanner as in the previ ous Example.

EXAMPLE 20 (Stabilization of polyamide) To 1 kg. of Nylon-6 chips having'nrel.=3.0, 0.5 percent of an additive as specified in Table 4 wasadded. The whole was thoroughly mixed, then extruded through a 20 mm. d:extruder into 50 denier sample filaments. Sample filament was subjectedto aging by keep ing it at 200 C in the air for 1 hour. The strength andthe elongation of the sample filament before and after aging wasmeasured, and the appearance of the sample filament was observed withnaked eyes.

TABLE 4 Tensile strength Elongation (kg/cm.)

Light Sambefore after before after resistance ple Additives aging agingaging aging (Appearance) slightly a No additives 960 6 H) 320 18 yellowb a-naphthyl 970 850 350 303 brown amine c N.N'-diphenyl 920 890 360 360dark brown paraphenylene diamine d Cytidine 945 920 38l 326 nearlycolorless e Uridine 936 912 352 320 do EXAMPLE 21 (Stabilization ofpolypropyrene) To g. of polypropylene, there was added 0.25 percent ofadditive as specified in Table 5. The whole was well mixed andcompression-moulded at 215 C. into 0.5 mm. thick sample sheets.

A test piece cut out from the sample sheet was exposed to U.V. rayirradiated from Fade-O-meter. During such irradiating operation, bendingof the test piece was conducted every 2 hours and the time duration fromthe beginning of the irradiating operation until the test piece isbroken was measured as brittling time which indicates light-resistanceof the sample sheet.

Another test piece cut out from the sample sheet was kept at C. in theair, during which the bending of the test piece was conducted every 2hours.

The time duration was similarly measured as brittlin g time whichindicates thermal stability of the sample sheet.

'Brittling time was measured for the sample sheet exposed to UV. ray.Brittling time was measured for the sample sheet aged by heat-treatment.

EXAMPLE 22 (Stabilization of polybutadiene) As degradation inhibitor forsynthetic rubber, well known are aromatic diamines, phenol derivatives,benzimidazoles, nickel dithiocarbomate and substituted phosphites. Noneof them affording satisfactory degradation inhibiting effect, superiordegradation inhibitors or stabilizers are longed for. The effect of thepyrimidine bases of the present invention to inhibit degradation byozone and heat is well justified by the results of following tests.

A mixture of 100 parts of synthetic rubber as specified in Table 6, 0.8part of N-cyclohexyl-2- benzothiazole-sulfenamide as avulcanization-accelerator, 5 parts of zinc flower, 2.5 parts of sulfur,2 parts of stearic acid and 2 parts of stabilizer as specified in Table6 was press-vulcanized at C. for 15 min. to form a sample.

The sample was exposed to ozone in an Ozone- Weather-Meter in which theconcentration of ozone was kept at 50 ppm, and the cracking of thesample was observed. While, a portion of the sample was maintained at 90C. in the air for 36 hours to measure thermal degradation, which isdefined by the formula:

with thermal degradation of the sample not containing TABLE 6 ThermalSam- Ozone degradation degradation ple synthetic inhibiting No. rubberAdditives 1(hr.) 3(hr.) (hr.) effect No l SBR additives l 2 (styrene- B-H- -H- 1.6

butadiene) copolymer) 3 B -l l- 2.5 4 Cytidine -H- 3.3 5 Uridine -H- -H--H- 3.1 6 Cytosine -H- H -H- 2.9 7 Thymine -H- 2.8 8 Cis-poly- N0 lbutadiene additives 8 +1- -ll- 1.3 10 B H-. 2.3 l l cytidine -ll- -ll-3.5 12 uridine -ll- -H- 3.2 13 cytosine +l- +1- 2.7

, phenylene diamine sold under the trademark Nocrack SlONA.

+ Very small cracks were observed. -ll- No cracks were observed.

Small cracks were observed.

- Large cracks were observed.

EXAMPLE 23 To 1 kg. of vinylidene chloride 80 vinyl chloride copolyrner(viscosity 1 c.p.s., measured at 120 C for 1 percent by weight solutionof the copolymer in orthodichlorobenzene), there were added 5 percent oftertiary-butyl-phenylsalicylate, 3 percent of di-N-butyl tin-dilaurateand 1 percent of cytidine. The whole mixture was throughly mixed in amortar, and then extruded with a small extruder at cylinder temperatureof 175 C.

1n the course of extruding operation, decomposition of vinylidenechloride, discoloration of strands, slabs and surface-coarsening ofstrands were not observed. Sample not containing cytidene was excludedinto the strands, which turned to light brown and there was a weak smellof hydrogen chloride gas near the spinnerets.

EXAMPLE 24 (Stabilization of polyester) A 2 l. autoclave was chargedwith 1 kg. of

-' polyethylene terephthalate (reduced viscosity: 0.97,

Another reference sample was prepared in the same manner as above exceptthat cytidine was not added, with a result that the strand finallybecame discolored like a straw.

The relative viscosity of the strand after heat-treatment was decreasedto 0.75.

EXAMPLE 25 (Stabilization of polyacetal) Into a 20 1. autoclave werecharged 9 mols of ecaprolactam and 1 mol of e-caprolactone.

Nitrogen stream was slowly introduced into the autoclave and the mixturewas heated at C. Then, 0.3 mol of methyl magnesium bromide and 0.3 molof N- acetyl caprolactam was added to the mixture and the whole mixturewas stirred for 15 minutes.

Then 40 mols of toluene was added to the mixture and the whole washeated to react at C. for 5 hours, giving polymer powder, which waswashed with 40 1. of 1 percent hydrochloric acid, and then with purewater until the washing water became neutral, and dried under vacuo, at60 C.

There was obtained polyester amide constituted of ecaprolactam 9:e-caprolactone 1.

A double-cone blender was charged with 1 kg. of polyoxymethylenediacetate (intrinsic viscosity: 1.92), 1.5 percent of above-obtainedpolyester-amide powder. 0.5 percent-of 4,4'-butylidene-bis(3-methyl-6-tert-butyl-l-formyloxy-benzene) and 0.1 percent of a compound asspecified in Table 7. The mixture was mixed and pelletized with a smallextruder at a cylinder temperature of 190 C. The pellets were formedinto a 3 mm. thick plate at a cylinder temperature of 190 C. and mouldtemperature of 85 C under the extruding pressure of 1,100 kg./cm

The properties of the plate was measured and shown in Table 7.

A three-necked flask was charged with 0.6 mol of sebacic aciddihydrazide, 1.0 mol of hexamethylene diamine and 1.5 mol of urea, whichwere then heated to melt and react at 205 C. with stirring in nitrogenstream for 200 minutes.

There was formed colorless transparent liquid which gradually turnedviscous and at last it became hazy white. Then the reaction system wasvacuumed to 1 mm Hg. where the reactant was kept for 300 minutes tocomplete the reaction, yielding colorless transparent polymer massin g.This mass could be formed into a clear thin film at C by means of alaboratory press.

To polyoxymethylene diacetate (intrinsic viscosity: 1.82) were added 0.9percent of above-obtained polymer in powder form, 0.4 percent of1,1,3-tris (2- methyl-4-hydroxy-5-tert-butylphenyl) butane and 0.1percent of an additive as shown in Table 8.

The whole mixture was extluded at a cylinder temperature of 190 8. intopellets, which were then injected into a mould maintained at 70 C. withinjecting pressure of 900 kg./cm A 3 mm. thick sample plate wasinjection-molded.

A test piece of this sample plate was heated at 222 C in the air for 90minutes and the weight loss of the piece was measured.

Whiteness in terms of Z value of another piece of the sample plate wasmeasured.

Another test piece of the sample plate was exposed to U.V. rayirradiated from Fade-O-Meter and the appearance of the test piece wasobserved as an indication of light resistance. The results are shown inTable 8.

TABLE 8 Appearance After 48 after 96 after 192 hours hours hours not notnot changed changed changed do Yellow Yellow R (36) Z value 99.3 99

ple Additives u Cytidine b 5-amino 98.7 99

cytidine c Uridine 99.] 99 -donot changed Yellow not changed (1 5,6-diamino Yellow uridine Note:

" R(%) is as defined in Table l. Z value is as defined in Table I.

What is claimed is:

1. Stabilized polymer composition which comprises (1) polymer materialselected from the group consisting of polyolefines, polydiolefines,polyurethanes, polyhaloolefines, polyacetals and their copolymers (2)0.001 10 percent by weight based on polymer material of at least onepyrimidine base of the general formula wherein R is a member selectedfrom the group consisting of hydrogen atom, hydroxyl, alkyl of one to 18carbon atoms; R is a member selected from the group consisting ofmonosaccharide of five to six membered ring such as and alkyl oracetyl-substituted monosaccharide of five to six membered ring; R is amember selected from the group consisting of hydrogen atom, alkyl of oneto 18 carbon atoms; and R is a member selected from the group consistingof amino and hydroxyl, and (3) at least one nitrogen containing compoundselected from the group consisting of polyamide copolymers,polyesteramides, dicarboxylic acid dihydrazide-ureadiamine condensatesand dicyandiamide.

2. Stabilized polymer composition as Claimed in claim 1, in which saidpolymer material is polyoxymethylene diacetate, polyoxymethylene dietheror copolyoxymethylene.

3. Stabilized polymer composition as claimed in claim 1, in which saidcomposition further contains stabilizing amounts of at least onephenolic antioxidant.

4. Stabilized polymer composition as claimed in claim 1, in which saidpyrimidine base is present in an amount ranging from 0.01 to 5 percentby weight based on said polymer material.

5. Stabilized polymer composition as claimed in claim 1, in which saidpolymer material is polyoxymethylene diacetate.

6. Stabilized polymer composition as claimed in claim 1, in which saidpyrimidine base is cytidine.

7. Stabilized polymer composition as claimed in claim 1, in which saidpyrimidine base is uridine.

8. Stabilized polymer composition as claimed in claim 1, in which saidpyrimidine base is cytidine and said composition additionally contains0.001 10 percent by weight based on said polymer material ofhexamethyleneadipamide-hexamethylene sebacamidecaprolactam-copolyamide.

9. Stabilized polymer composition as claimed in claim 1, in which saidpyrimidine base is cytidine and said composition additionally contains0.001 10 percent by weight based on said polymer material ofpolyaminotriazole prepared from sebacic acid hydrazide.

10. Stabilized polymer composition as claimed in claim 1, in which saidpyrimidine base is cytidine and said composition additionally contains0.001 10 percent by weight based on said polymer material of ureaadipicacid dihydrazide-hexamethylenediamine-condensate.

ll. Stabilized polymer composition as claimed in claim 1, in which saidpyrimidine base is uridine and said composition additionally contains0.001 10 percent by weight based on said polymer material of ureaadipicacid dihydrazide-hexamethylenediamine-condensate.

l2. Stabilized polymer composition as claimed in claim 1, in which saidpyrimidine base is cytidine and said composition additionally contains0.001 l0 percent by weight based on said polymer material ofdicyandiamide.

l3. Stabilized polymer composition which comprises (1) polyamides orpolyesters, (2) 0.001 10 percent by weight based on polymer material ofat least one pyrimidine base of the general formula wherein R. is amember selected from the group consisting of hydrogen atom, hydroxyl,alkyl of one to 18 carbon atoms; R is a member selected from the groupconsisting of monosaccharide of five to six membered ring such as Home HHome 1 1?" t? HOHzC and

2. Stabilized polymer composition as Claimed in claim 1, in which saidpolymer material is polyoxymethylene diacetate, polyoxymethylene dietheror copolyoxymethylene.
 3. Stabilized polymer composition as claimed inclaim 1, in which said composition further contains stabilizing amountsof at least one phenolic antioxidant.
 4. Stabilized polymer compositionas claimed in claim 1, in which said pyrimidine base is present in anamount ranging from 0.01 to 5 percent by weight based on said polymermaterial.
 5. Stabilized polymer composition as claimed in claim 1, inwhich said polymer material is polyoxymethylene diacetate.
 6. Stabilizedpolymer composition as claimed in claim 1, in which said pyrimidine baseis cytidine.
 7. Stabilized polymer composition as claimed in claim 1, inwhich said pyrimidine base is uridine.
 8. Stabilized polymer compositionas claimed in claim 1, in which said pyrimidine base is cytidine andsaid composition additionally contains 0.001 - 10 percent by weightbased on said polymer material of hexamethyleneadipamide-hexamethylenesebacamide-caprolactam-copolyamide.
 9. Stabilized polymer composition asclaimed in claim 1, in which said pyrimidine base is cytidine and saidcomposition additionally contains 0.001 - 10 percent by weight based onsaid polymer material of polyaminotriazole prepared from sebacic acidhydrazide.
 10. Stabilized polymer composition as claimed in claim 1, inwHich said pyrimidine base is cytidine and said composition additionallycontains 0.001 - 10 percent by weight based on said polymer material ofurea-adipic acid dihydrazide-hexamethylenediamine-condensate. 11.Stabilized polymer composition as claimed in claim 1, in which saidpyrimidine base is uridine and said composition additionally contains0.001 - 10 percent by weight based on said polymer material ofurea-adipic acid dihydrazide-hexamethylenediamine-condensate. 12.Stabilized polymer composition as claimed in claim 1, in which saidpyrimidine base is cytidine and said composition additionally contains0.001 - 10 percent by weight based on said polymer material ofdicyandiamide.
 13. Stabilized polymer composition which comprises (1)polyamides or polyesters, (2) 0.001 - 10 percent by weight based onpolymer material of at least one pyrimidine base of the general formula14. Stabilized polymer composition as claimed in claim 13, in which saidcomposition further contains stabilizing amounts of at least onephenolic anti-oxidant.